Evaporator and absorber unit for absorption refrigeration systems



Sept. 21, 1954 L. M NEELY 2,539,465 EVAPORATOR AND ABSORBER UNIT FORABSORPTION REFRIGERATION SYSTEMS Filed June 30, 1951 3 Sheets-$heet 14&4 4770/?[7 ENTOR.

Sept. 21, 1954 L. MCNEELY 2,689,465

EVAPORATOR AND ABSORBER UNIT FOR ABSORPTION REFRIGERATION SYSTEMS FiledJune 30, 1951 3 Sheets-Sheet 2 000mm nmemnmsa Q99 93 84 m 83 I 0C IINVENTOR. W F M% I L I 50a BY Sept. 21, 1954 MCNEELY 2,689,465

L. EVAPORATOR AND ABSORBER UNIT FOR ABSORPTION REFRIGERATION SYSTEMSFiled June 30, 1951 3 Sheets-Sheet 3 IN VEN TOR.

Patented Sept. 2}, 1954 EVAPORATOR AND ABSORBER UNIT FOR ABSORPTIONREFRIGERATION SYSTEMS Lowell McNeely, Evansville, Ind., assignor toServe], Inc., New York, N. Y., a corporation of Delaware ApplicationJune 30, 1951, Serial No. 234,515

8 Claims.

The present invention relates to refrigeration and more particularly toan evaporator and absorber construction for absorption refrigerationsystems. 7

When small refrigerationunits are used for air conditioning, therefrigerant may be evaporated at the interior of a finned coil and the"air to be cooled passed over the exterior of the transfer coils atdifferent locations where the air is to be cooled. One of the objects ofthe present invention is to provide an evaporator in the form of spacedtubes over which a primary refrigerant trickles by gravity and throughwhich a secondary refrigerant is circulated.

Another object is to provide a combined evaporator and absorber forabsorption refrigeration.

systems having tubes arranged in side-by-side open communication witheach other in an enclosing shell with one group. of tubes connected toprovide an evaporator and another group of tubes connected to provide anabsorber.

Another object is to arrange the tubes in vertical rows with means todistribute liquid refrigerant and absorbent onto the uppermost tubes ofdifferent rows and so forming the tubes as to cause the liquid to dripat selected points from each tube onto the next lowermost tube from thetop to the bottom of the. rows to produce an equal distribution ofliquid over the entire surface of the tubes of each row.

Another object is to drip liquid refrigerant from the top to the bottomof a row of evaporator I tubes and automatically lift refrigerant liquidupwardly from the bottom of theevaporator and distribute it overthesurface of the lower tubes of the row.

Still another object of the invention is to provide a combinedevaporator and absorber of simple and compact construction comprisingbanks of tubes in an enclosing shell connected to provide a centralevaporator section andabsorber sections at either side of the evaporatorsection.

These and other objects will become more apparent from the followingdescription and drawings in which like reference characters denote likeparts through the several views. It is to be expressly understood,however, that the drawings are for the purpose of illustration only andnot a definition of the limitation of the invention, reference being hadfor this purpose to the appended claims. In the drawings:

Fig. 1 is a diagrammatic view of an air conditioning system having avacuum type absorption refrigeration unit incorporating the evaporatorand absorber construction of the present invention;

Fi 2 is a transverse sectional view showing one end of the combinedevaporator and absorber in detail and the arrangement of the banks oftubes constituting a centrally located evaporator and absorber sectionsat opposite sides of the evaporator;

Fig. 3 is a sectional view of a portion of the opposite end of theevaporator from that illustrated in Fig. 2 and showing the sectionalarrangement of the tubes and connecting means for delivering secondaryrefrigerant thereto;

' Fig. 4 is a side elevational view partly in section showing onevertical row of tubes, the liquid distributing means overlying the rowand the spaced drip formers at the bottom of each tube;

Fig. 5 is a side elevational view of the lower portion of a vertical rowof tubes constituting the evaporator and showing the capillary groovingon the lower two tubes and the pans under lying the grooved tubes;

Fig. 6 is a plan view partly in section of the liquid distributor forsupplying refrigerant to the bank of evaporator tubes; and V Fig. '7 isa sectional plan view of the lower portion of the evaporator and showingthe plurality of grooved tubes overlying each pan.

Referring to Fig. 1 of the drawings, the air conditioner comprises aprimary vacuum type absorption refrigeration system Ill, an auxiliarycooling system H containing a secondary refrigerant for removing heatfrom the air to be conditioned and transferring it to the primaryrefrigeration system at a relatively low temperature, and a tertiarycooling system I2 for removing heat from the primary refrigerationsystem at relatively high temperature. y

The primary vacuum type absorption refrigeration system as illustratedin the drawings comprises. in general a combined generator and vaporliquid-lift l3, a condenser I 4, a combined evaporator and absorber I5constituting the subject matter of the present invention, and. a liquidheat exchanger I5 interconnected for the circulation of refrigerant andabsorbent. The combined generator and vapor liquid-lift I3 is describedand claimed in a copending application for United States Letters Patentof Walter M. Simpson Serial No. 219,777, filed April 7, 1951. Suffice itto state herein that the element I3 comprises a single conduit having anupper vapor liquid-lift portion l1 and a depending portion |8 with anextended wall for increasing the heat transfer surface. The vaporliquid-lift I7 and depending portion l8 are enclosed in a jacket l9providing a heating chamber 20 therebetween. A steam supply conduit 2|is connected to the bottom of the jacket H] to supply the requiredamount of steam to operate the refrigeration system at full capacity.Steam supplied to the heating chamber 2 "is maintained at atmosphericpressure by a vent tube 22 at the upper end "of the jacket I9 and a.condensate drain 23 is provided at the lower end of the jacket.

A separating chamber 24 surrounds the upper end of the lift conduit I!and has suitable .baflies 25 for separating refrigerant vapor fromabsorption solution delivered from the lift conduit. A vapor pipe 25connects the separating chamber 24 to the condenser I4 and a liquid pipe27 connects the outlet from the condenser to a flash chamber 28.Condenser l4 may be of any known type which hermetically seals therefrigerant from the cooling medium and in the illustrated embodimentcomprises a chamber 29 with tubes 30 extending therethrough from aninlet header 3| to an outlet header The liquid refrigerant pipe 21 is inthe form of a U-tube to provide a liquid trap for maintaining a liquidcolumn to balance the difference in pressure between the condenser I4and combined evaporator and absorber l5.

Flash chamber 28 is a vessel which receives liquid refrigerant .from theliquid pipe 27 at the high temperature of the condenser I4 and flashes aportion of the refrigerant to cool the remainder to a low temperaturecorresponding to the boiling point of the refrigerant .at the lowpressure in .the combined evaporator and absorber I5. Such flashing is aviolent boiling and is performed prior to the introduction of therefrigerant into the evaporator to prevent agitation and splashing. Avapor pipe 34 connects the flash chamber 28 above the liquid leveltherein to the top of the combined evaporator and absorber l and aliquid pipe 35 connects the bottom of the flash chamber to a liquiddistributor 35, later to be described in detail.

The combined evaporator and absorber I5 is shown in detail in Figs. 2through 7 but for purposes of illustrating its relationship in therefrigeration system it is shown diagrammatically in Fig. 1. Asillustrated diagrammatically, the combined evaporator and absorber I5comprises a closed vessel or shell 31 having .an evaporator coil 38 andan absorber coil 39 in open communication with each other. Theevaporator coil 38 is of serpentine form and arranged vertically withstraight tube sections located one above the other. Liquid refrigerantis distributed by the liquid distributor 36 onto the top of theuppermost straight sec.- tion .of the evaporator coil .38 and drips fromeach section to the next lowermost section from the top to the bottom ofthe coil. The absorber standing at some level a: in U-tube 21, at level'4 coil 39 also is of serpentine form having straight sections arrangedone over the other and a liquid distributor 40 delivers absorptionsolution for gravity flow over the exterior of the coil from eachstraight section to the next lowermost section throughout the height ofthe coil. Absorption solutionweak in refrigerant flows by gravity fromthe separating chamber 24 to the liquid distributing means 40 for theabsorber coil 39 in a path of flow comprising conduit 4|, inner passage42 of the liquid heat exchanger l6 and conduit 43 connected to theliquid distributor. Absorption solution strong in refrigerant flows bygravity from the shell 31 to the base of the combined generator andvapor liquidlift H5 in a path of flow comprising conduit 44, outerpassage 45 of the liquid heat exchanger l6, conduit 46, leveling vessel41 and conduit 48. Leveling vessel 41 is for the purpose of maintaininga substantially constant liquid level of solution and is connected by avent pipe 49 to the separating chamber 24. The combined generator andvapor liquid-lift l3 and condenser I4 operate at a pressurecorresponding to the vapor pressure of the refrigerants at itscondensing temperature and the combined evaporator and absorber I5operates at a lower pressure corresponding to the vapor pressure of therefrigerant in the absorber. During operation of the refrigerationsystem, liquid columns will stand in U-tube 21 and conduits '43 and 44to balance the difference in pressure, the liquid 1 in conduit 4|connectedto conduit 43 through heat exchanger H5, at level a in conduit44., and at a level to in the reservoir vessel 47.

Underlying the evaporator coil 38 .is a tray 50 for collecting anyexcess unevaporated liquid refrigerant and delivering'it toaconcentration control vessel 5|. The bottom of the concentration controlvessel 5| is connected to the base of the combined generator and vaporliquidlift .|3 by a conduit 52 and the top of the vessel is connected tothe evaporator by a vent pipe 53. Unevaporated liquid refrigerantaccumulates in the concentration control vessel 5| to increase theconcentration of the absorption solution until an equilibrium is reachedat which all of the refrigerant is evaporated in the evaporator, theheight of the liquid column and amount of liquid refrigerant stored inthe concentration vessel being controlled by the difference in pressurebetween the high and low pressure sides of the system.

A secondary refrigerant is circulated in the auxiliarycooling system Hin heat exchange relation with the evaporator and air in an enclosure Rto be cooled. The auxiliary cooling system comprises the evaporator coil38 and a heat exchange coil 54 in the room or rooms R to be cooled. Aconduit 55 connects the upper end of the evaporator coil 38 to one endof the heat exchange coil 54, a conduit 56 connects the opposite end ofcoil 54 to. a circulating pump 51 and a conduit 58 connects the outletfrom the pump to the lower end of the evaporator coil to complete acircuit. Pump 51 is driven by an electric motor 53 for circulating thesecondary refrigerant through the evaporator coil 38 and heat exchangecoil 54, successively.

The tertiary cooling system l2 for removing heat from the refrigerationapparatus comprises the absorber coil 39 and tubes 30 of the condenserl4. A source of cooling medium such as cooling tower 60 delivers coolingwater for flow through a cooling water through the cooling system and afan 65 at the top of the tower circulates air in contact with thecooling water flowing there- .through to reduce its temperature byevaporative cooling. A by-pass 66, as described and claimed in anapplication forLetters Patent of Harry C. Shagalofi, filed concurrentlyherewith, is connected between the inlet and outlet conduits 6| and 62leading to and from the absorber coil 39 .to shunt the absorber at thebeginning of a period of operation as controlled by a valve 61.

A purging device 68 is provided for continuously withdrawingnon-condensable gases from the shell 31 of the combined evaporator andabsorber I and a restricting conduit 68a continuously passes gases fromthe condenser to the shell while limiting the amount of vapor flowing,therethrough. The purge device 68 is in the form of a vessel connectedto the combined evaporator and absorber shell 31 by a suction tube 69.Absorption solution weak in refrigerant is supplied to the purge vessel68 from conduit 43 through a connecting pipe 18 and a fall tube Hconnects the .bottom of the vessel to a separating chamber I2.

A riser "I3 connects the separating vessel I2 adjacent the top thereofto a gas storage vessel 14 and aliquid line I5 connects the separatingvessel to conduit 48 leading to the base of the combined generator andvapor liquid-lift I3.

In accordance with the present invention the combined evaporator andabsorber I5 shown diagrammatically in Fig. l'comprises a plurality oftubes arranged in vertical rows in closely adjacent side-by-siderelationship with the rows in open communication with each other. Atleast one of therows of tubes constitutes an evaporator while one ormore of the other rows constitutes the absorber. Alternate tube rows oralternate pairs of tube rows may constitute the evaporator v andabsorber, respectively, within the scope of .the present invention.

In the preferred embodiment of the invention illustrated in detail inFigs. 2 to '7, the combined evaporator and absorber I5 comprises banks88, 8| and 8 2 of tubes 83. The bank of tubes 88 constitutes theevaporator, illustrated diagrammatically as a single coil 38 in Fig. 1,located centrally of the shell 31 while the banks of tubes 8| and 82constitute separate absorber sections, illustrated diagrammatically as asingle coil 39 in Fig. 1, lo-

cated at each side of the evaporator tube bank 88, closely adjacentthereto and in open communication therewith. The tubes 83 of each of thebanks .88, .8I and 82 are all arranged in generally the same way, thatis, one over the other in vertical rows, see Figs. 2 and 4, and the endsof adjacent tubes in each row are connected by U-shaped couplings 84 toprovide a continuous serpentine coil.

The tubes of each bank 88, 8| or 82 are supported in a frame havingspaced angle-iron side rails 85 at the bottom and upright rectangularplates 96 welded to the ends and middle of the bottom rails, see Fig. 4.The rectangular plates 86 extend throughout the width and height oftherespective banks 88, 8| and 82, see Fig. 2, and have right angularflanges 81 at each side, see Figs. 4 and 7, right angular flanges 88 atthe top and aligned perforations 89, see Figsg5 and'f.

6 In assembling a bank of tubes 88, 8| or 82, tubes 83 are insertedthroughout the aligned perforations 89 in the plates 86 of the frame andthe U-shaped couplings 84 inserted in the ends of adjacent tubesalternately at opposite ends thereof and brazed or welded thereto toform a continuous serpentine coil 38 or 39 of each vertical row oftubes. The inlet ends of the plurality of serpentine coils of the bankare connected by a header 98 having a supply pipe 9| and the outlet endsof the coils are connected by a header 92 having a discharge pipe 93.Mounted on the V flanges 88 at the top of the plates is a liquiddistributor 36 or 48 as illustrated in Figs. 2, 4 and 6. The liquiddistributor comprises a plurality of parallel troughs 94 connected bytransverse end troughs 95. Each trough 94 is of a width corresponding tothe distance between the rows of tubes 83 and has walls 96 overlying thecenter of adjacent rows of tubes throughout their length. A U-shapedsyphon plate 91 overlies each wall 96 of the liquid distributor 36 or 48and has spaced capillary grooves 98 for feeding liquid onto the top ofthe uppermost tube 83 of a row at spaced points therealong. Thus, ifthere are six vertical rows of tubes in a bank, three troughs asillustrated in Fig. 6 will provide six walls for delivering liquid ontothe respective rows of tubes. Extending transversely of the troughs 94is a closed tube or vessel 99 having an orifice I88 for each trough 94at opposite sides of the vessel 99 to feed liquid thereto. Preferably,bafiles I8I are provided in the troughs 94 adjacent the orifice I88 todampen the flow of liquid and prevent agitation. Liquid may be suppliedto the closed tube or vessel 99 from a laterally extending feed pipe I82 used onthe tube banks 8| and 82 constituting absorber sections asillustrated in Fig. 4 or by a vertical feed pipe 35 used on the tubebank constituting the evaporator, as illustrated in Figs. 2 and 6. I

Each of the tubes 83 of the banks 88, 8| and 82 has depending dripformers I84 at spaced points along its bottom as illustrated in Fig. 4.Preferably such drip formers are formed by striking one side of the tubewith a straight tool in a direction at right angles to the axis of thetube, as described and claimed in a copending application for LettersPatent of Eugene P. W'hitlow, Serial No. 102,863, filed July 2, 1949.

The tubes 63 of bank 88 constituting the evaporator are arranged invertical rows from the top to the bottom of the bank, but are connectedat their ends to provide separate groups or sections I85, four of suchsections being illustrated in Fig. 2 of the drawings. The inlet andoutlet headers 98 and 92 for each section I are illustrated in Fig. 3and the supply pipes 9| for the plurality of inlet headers 98 areconnected together by a main conduit 9 Ia while the discharge pipes 93from outlet headers 92 for the sections I85 are connected together by adischarge conduit 93a so that secondary refrigerant will flow inparallel through the separate sections to reduce the pressure drop inthe coils. While the majority of the tubes 83 are provided with spaceddepending drip formers I84, several of the lower tubes 83a of each rowof the evaporator bank 88 are formed with peripheral capillary groovesas described and claimed in United States Letters Patent to John G.Reid, Jr.,

No. 2,485,844, issued October 25, 1949. As illus- 7 in the preferredembodiment, one 50a underlying the next to the bottom tube of all of therows and a second 501) underlying the lowermost tubes of all of therows. The upper pan 50a has side walls on three sides and the bottom ofthe pan at its open end overlies the lower pan 50b to deliver liquidthereto. The lowermost pan 50b has side walls around its entireperiphery. The pans 50a and 50b are so arranged with respect to tubes830, that liquid will be lifted from the pans by capillary action in thegrooves 83b and distributed over the surface of the tubes. A drain tube|08 projects a predetermined distance above the bottom of the pan 50band constitutes an overflow pipe connected to the concentration controlvessel The banks of absorber tube sections 8| and 82 have tubes 83 withdepending drip formers I04 arranged in vertical rows and alternatelyconnected at opposite ends to provide a plurality of vertically arrangedserpentine coils extending throughout their height. The absorber tubebanks 8| and 82 are supported on spaced brackets l 09 and H0, see Fig.2, at each end of the shell 31, the bottom rails 05 and cross plates 80of the frames resting on the top of the brackets. The evaporator tubebank 80 is supported between the tube banks 8| and 82 by angle ironrails III on the flanges 81 resting on rails l |2 projecting from theupright legs of brackets |09 and I Hi. It will be understood that theevaporator tube bank 80 and absorber tube banks 8| and 82 are completelyfabricated as sub-assemblies and mounted in the shell 3? as separateunits with the supply and discharge conduits 9| and 93 for the coils andthe absorbent and refrigerant feed pipes I02 and 35 projecting outwardlyfrom the shell before the end plates of the shell are assembled and thejoints welded or brazed to hermetically seal the combined evaporator andabsorber l5. The absorbent feed pipes I02 are preferably connected tosupply conduit 43 and the chilled water supply and exhaust pipes 9| and93 are connected to mains 9m and 93a at the exterior of the shell 31.One form of the invention having now been described in detail, the modeof operation of the air conditioner is explained as follows.

To initiate operation of the complete air conditioning apparatusillustrated in Fig. 1, steam is supplied through the conduit 2| to theheating chamber of the combined generator and vapor liquid-lift l3 toheat the solution therein. Refrigerant vapor expelled from absorptionsolution lifts the latter in the lift tube I! at a controlled rate intothe separating chamber 24. Vapor flows through the baffles and vaporpipe 26 into the condenser l4 and absorption solution weak inrefrigerant flows by gravity to the liquid distributor 40 in a pathincluding the'conduit 4|, inner passage 42 of heat exchanger l6 andconduit 43.

Simultaneously with the supply of steam to the combined generator andvapor liquid-lift [3, cooling water is supplied from the cooling tower00 through the conduit 6|, by-pass 60, and conduit 62-to the header 3|of condenser Ml. Cooling water flows from header 9| through the tubes 30to header 32 and from the header through the conduit 63 back to thecooling tower 60. The flow of cooling water through the tubes 30 ofcondenser 14 removes the heat of vaporization and condenses therefrigerant vapor to a liquid. The liquid refrigerant flows from thecondenser l4 through the U-shaped liquid pipe 21 to the flash chamber 28and from the flash chamber through 8 the liquid pipe 35 to therefrigerant distributor 36.

Liquid refrigerant and absorbent is siphoned from the distributors 36and 40 through the spaced capillary grooves 98 of syphon plates 91, seeFig. 6, onto the uppermost tubes 83 of the respective banks 80, 8| and82 and drips over successive tubes from the top to the bottom of theevaporator and absorber simultaneously. Due to the affinity of therefrigerant, Water, for the absorbent, lithium bromide solution, therefrigerant evaporates at a low pressure and temperature and the vaporis absorbed in the absorption solution. Any unevaporated liquidrefrigerant drips into the lower pan 5% and flows into the concentrationcontrol vessel 5| to adjust the concentration of the absorbent until anequilibrium condition reached at which all of the refrigerant willevaporate as it drips from coil section to coil section from the top tothe bottom of the evaporator coil 38. Absorption solution strong inrefrigerant flows from the combined evaporator and absorber shell 31back to the base of the combined generator and vapor liquid-lift |3 in apath of flow including the conduit 44, outer passage 45 of liquid heatexchanger l0, conduit 46, leveling vessel 41 and conduit 48.

Simultaneously with the initiation of the primary absorptionrefrigeration system ID the pump 51 in the auxiliary cooling system Mwill be initiated to circulate a secondary refrigerant through theevaporator coil 38. The heat exchange coil 54 in room R will remove'heatfrom the air and transfer it through the walls of the evaporator coil 38to the primary refrigerant on the outside surface thereof. Thus, theauxiliary cooling system l of the air conditioner operates to removeheat from the air in a room or rooms R and transfer it to therefrigerant in the primary refrigeration system H] and the primaryrefrigeration system then transfers the heat to the tertiary coolingsystem [2. After the primary refrigeration system has been operating fora period of time sufficient to insure a full loading of the evaporatorboth internally and externally, the valve 61 in the by-pass 66 will beclosed to cause the cooling water to flow through the absorber coil 39and condenser l4 successively.

Referring to Figs. 2 to 7, the liquid refrigerant supplied to the liquiddistributor 36 through the supply pipe 35 enters the closed vessel 99and is distributed through the orifices I00 into the troughs 94overlying the centrally located bank of evaporator tubes 83. The liquidrefrigerant continuously siphons from the troughs 94 through thecapillary grooves 98 in the distributing plates 91 onto the uppermosttubes of each of the rows of tubes constituting the evaporator. Theliquid refrigerant spreads over the upper smooth surface of the tubesand then accumulates on the depending drip formers I04 from which itdrips onto the next lowermost tube from the top to the bottom of theevaporator. Any liquid refrigerant dripping from the next to the bottomtube 83a of the rows of tubes is caught by the upper pan 50a whichdirects it into the lower pan 50b. The upper and lower pans 50a and 5012contact the bottom of the grooved tubes 83a and the capillary grooves831) lift the liquid from the pans and saturate the surfaces of thetubes above the liquid level to insure maximum evaporation of therefrigerant. However, when the level of the liquid refrigerant in thelower pan 50b rises above the end of the drain tube I08 the liquidrefrigerant will overflow into the concentration control vessel 5|.

9' 3 Absorption liquid delivered to the liquid distributor 40 for eachabsorber section 8| and 82 l is distributed by the closed vessel 99 intothe troughs '94 overlying the rows of the absorber tubes and isdistributed along the uppermost tubes of each row in the same wayrefrigerant is distributed over the bank of evaporator tubes 80. Liquidabsorbent drips from each tube 83 onto the top of the next lowermosttube from the top to the bottom of the absorber sections 8| and 82.Refrigerant vapor from the evaporator 88 is absorbed in absorptionliquid as it flows over the tubes and at the lowermost tubes theabsorption liquid drips into the enclosing shell 31 and flows to theoutlet conduit 44.

It will now be observed that the present invention provides a novelconstruction of combined evaporator and absorber comprising verticalrows of tubes arranged in side-by-side relation and in opencommunication witheach other in a single hermetically sealed, enclosingshell. It will further be observed that the present invention providesfor connecting the tubes to provide a centrally located evaporatorsection with absorber sections on either side thereof. It willstilljfurther be observed that the present invention provides a combinedarrangement of tubes in the evaporator section having drip formers foruniformly distributing refrigerant over all except the lowermosttubesand capillary grooves on the periphery of the lowermost tubes to liftrefrigerant over their surface.

While a single embodiment of the invention is herein illustrated anddescribed, it will be understood that modifications may be made in theconstruction and arrangement of the elements without departing from thespirit or scope of the invention. Therefore, without limitation in thisrespect, the invention is defined by the following claims.

Iclaim:

1. In an absorption refrigeration system, an hermetically sealed shellenclosing both the evaporator and absorber at substantially the samelevel, said combined evaporator and absorber comprising a plurality oftubes in said shell and arranged in vertical rows, said rows being in,closely adjacent side-by-side relation and in open communication witheach other,

means to deliver liquid refrigerant onto the ex-' terior of theuppermost tube of at least one row, means to deliver liquid absorbentonto the exterior of the uppermost tube of at least one of the otherrows of tubes, the liquid dripping from each tube onto the nextlowermost tube from the top to the bottom of its respective row, meansfor flowing a medium to be cooled through the interior of the row oftubes over which the liquid refrigerant is distributed, and means forflowing a cooling medium through the interior of a row of tubes overwhich the absorbent is distributed.

2. In a two-pressure absorption refrigeration system of the type inwhich the difference in pressure is maintained by pressure balancingliquid columns, a combined evaporator and absorber for reducing theoverall height f the system comprisin an hermeticallysealed shell, aplurality of coils arranged vertically in sideby-side relation in opencommunication with each other in said shell, each of said coils havingsections arranged one over the other, means to deliverliquid refrigerantonto the exterior of the uppermost section of at least one of the coils,means to deliver liquid absorbent onto the exterior of the uppermostsection of at least one of the other coils, the liquid on the respectivecoils dripping from each section onto the next lowermost section fromthe top to the bottom of the coil, means for deliverin a medium to becooled for flow through the interior of the refrigerant coil, and meansfor delivering a cooling medium for flow through the interior of theabsorbent coil.

3. In an absorption refrigeration system, a combined evaporator andabsorber comprising an hermetically sealed shell, an evaporator arrangedcentrally in said shell, an absorber having sections at each side ofthe. evaporator and in open communication therewith, said evapora torand absorber sections comprising tubes connected to provide separatepaths of flow, means for distributing liquid refrigerant and absorbenton the tubes of the evaporator and absorber, respectively, to wet theexterior surfaces thereof,

.means for flowing a fluid to be cooled through the interior of theevaporator tubes, and means for flowing a cooling medium through theinterior of the absorber tubes.

4. In an absorption refrigeration system, a combined evaporator andabsorber comprising a single hermetically sealed cylindrical shell, aplurality of tubes in said shell connected to provide a centralevaporator section and absorber sections at each' side of the evaporatorsection, the tubes of said evaporator and absorber sections beingarranged one over the other in vertically aligned rows in closelyadjacent side-byside relationship and in open communication with eachother, means for supplying liquid refrigerant and absorbent to theuppermost tubes of the evaporator and absorber, respectively, whichdrips from each tube to the next lowermost tube from the top to thebottom of the rows, means for flowing a medium to be cooled through thetubes constituting the evaporator, and means for flowing a coolingmedium through the rows of tubes constituting the absorber.

5. In an absorption refrigeration system, a combined evaporator andabsorber comprising an hermetically sealed shell having spaced brackets,an evaporator comprising a frame located between the brackets andsecured thereto, said frame mounting a bank of tubes arranged one overthe other in vertical alignment,

absorber sections at either side of the evaporator with each sectioncomprising a frame resting on the brackets and mounting a bank of tubesarranged one over the other in vertical alignment, a liquid distributormounted on the top of each of the evaporator and absorber section framesand having means for delivering liquid refrigerant and absorbent ontothe upper tube of each row of the respective banks of tubes, said liquiddripping from each tube to the next lowermost tube from the top to thebottom of each row, means for flowing a medium to be cooled through thebank of evaporator tubes, and means for flowing a cooling medium throughthe banks of tubes of the absorber sections.

6. In a refrigeration system, an evaporator comprising an hermeticallysealed shell, a bank of tubes arranged one over the other in verticallyaligned rows and connected to provide separate paths of flow, liquiddistributing means for supplying liquid refrigerant uniformly along thetop of the uppermost tube of each row which drips from the bottom ofeach tube onto the top of the next lowermost tube from the top to thebot tom of the evaporator, a pan underlying the evaporator to receiveany surplus liquid refrigcomprising an hermetically sealed shell, a bankof tubes arranged one over the other in vertically aligned rows andconnected to provide parallel paths of flow, the lower tubes of each rowhaving peripheral capillary grooves, the remainder of the tubes of eachrow having a plain upper surface and spaced depending drip formers, aliquid distributor for delivering liquid refrigerant onto the uppermosttube of each row uniformly throughout its length, said liquidrefrigerant flowing over the plain surface off each tube and drippingfrom the drip formers onto the next lowermost tube from the top to thebottom of the row; a pan underlying the bank of tubes to receive liquidrefrigerant, and the capillary grooves on the lower tubes lifting liquidrefrigerant from the pan to wet their surface above the liquid level.

8,. In a refrigeration system, an evaporator comprising an hermeticallysealed shell, a plurality of serpentine coils arranged one over theother in vertical rows in said shell, the corresponding coils in eachrow being connected to provide a plurality of separate coil sections,each of the coils having longitudinal tube portions 12 arranged one overthe other from the. top to the bottom of a row, a plurality of the lowertubes of. each row having peripheral capillary grooves. the remainder ofthe tubes of each row having a plain upper surface and spaced dependingdrip; formers. a liquid distributor for delivering. liquid refrigerantonto the uppermost tube of each. row uniformly throughout. its length,said liquid refrigerant flowing over the plain surface of each tube anddripping from the drip formersv onto the next lowermost tube from thetop to the. bottom of the row, a pan underlying each horizontallayer ofcorresponding grooved tubes of adjacent coilsl the upper pan havingmeans for directing.

liquid refrigerant into the next lowermost panv and the capillarygrooves lifting liquid from the pans. over the surface of the tubesabove the liquid level.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,031,885 Stratton July 9, 1912 1,526,605 Mather Feb. 17, 19252,323,186 Andersen June 29, 1943. 2,399,916 Edberg May '7, 19462,485,844 Reid Oct. 25, 1949 2,565,943 Berestneif Aug. 28, 19512,568,891 I Kals Sept. 25, 1951

